This invention relates generally to locking mechanisms for use with folding tools such as pocket knives and other hand tools. More particularly, the invention relates to a sturdy and easily operable mechanism that locks the working portion of a tool in an open position, and allows the working portion to be quickly moved into a closed position.
Folding tools such as knives and the popular xe2x80x9cmultitoolsxe2x80x9d have become ubiquitous and are well known in the art. Such tools are suitable for many purposes, and the following U.S. patents are just a few of the many that describe useful innovations in the field of knives: U.S. Pat. No. 1,030,058 to Doles, U.S. Pat. No. 1,189,005 to Seely, U.S. Pat. No. 2,188,762 to Schrade, U.S. Pat. No. 3,868,774 to Miori, U.S. Pat. No. 4,2233,737 to Poehlmann, U.S. Pat. No. 4,240,201 to Sawby et al., U.S. Pat. No. 4,274,200 to Coder, U.S. Pat. No. 4,451,982 to Collins, U.S. Pat. No. 4,502,221 to Pittman, U.S. Pat. No. 4,670,984 to Rickard, U.S. Pat. No. 4,837,932 to Elsener, U.S. Pat. No. 4,896,424 to Walker, U.S. Pat. No. 5,060,379 to Neely, U.S. Pat. No. 5,425,175 to Rogers, U.S. Pat. No. 5,461,786 to Miller, U.S. Pat. No. 5,737,841 and U.S. Pat. No. 6,122,829 both to McHenry et al. There are many other patents that describe useful innovations in the field of other folding tools.
Locking mechanisms are useful additions to folding tools, and many of the aforementioned patents describe different mechanisms for locking tool blades in an open position. For example, the patents to Sawby et al., Miller and Seely each disclose a variation of a xe2x80x9clock backxe2x80x9d mechanism. This construction entails forming a notch on a tang of the blade that is engaged by a lug located on the spine of the knife to lock the blade in an open position. The patents to Neely and Collins each disclose another type of locking mechanism. As disclosed in these patents, a blade has a tang that is engaged by a member to prevent the blade from rotating from its open position. For example, in Collins, a slidable bolt is biased towards the tang to lock the blade in its open position. A shortcoming with Collins""s knife construction is that the bolt is generally parallel with the blade, and the mechanism depends on the spine of the handle for strength. Neely""s knife suffers from the same disadvantage as Collins"", and from the fact that the blade may be unlocked inadvertently by pulling the blade axially away from the handle during a normal cutting motion of the knife. The two patents mentioned above to McHenry et al. describe yet another blade locking mechanism in which a spring biased pin extending transverse to the blade is longitudinally movable in the handle and engages the tang of the blade to lock it in the open position. This locking mechanism is exceedingly strong and easy to operate.
Despite the many different kinds of locking mechanisms there is a need for still a greater variety of devices that allow the working portion of a folding tool xe2x80x94whether the tool is a knife blade or a pliersxe2x80x94to be reliably locked in the open position.
The present invention provides a locking mechanism for a folding tool that is structurally distinct from the prior art. The locking mechanism described herein is strong and reliable, easily operated, versatile and aesthetically attractive.
The mechanism is adaptable to virtually any folding tool, including knives, multitools, and other hand tools of a similar nature. It is described herein in accordance with one preferred embodiment of a knife. The knife comprises an elongate handle having opposed body side wall sections defining an elongate slot or groove therebetween. At least one knife blade is pivotally attached to the handle at one end. The blade is movable between a closed position in which the blade is received within the groove of the handle, and an open position in which the blade is extended away from the handle and exposed. The blade has a working portion that extends away from the handle when in its open position and a tang portion, which is located within the groove of the handle when the blade is in its open position.
In one preferred embodiment, one of the side wall sections defines a panel having a pair of opposed and overlapping, generally U-shaped slots formed therein. The side wall is formed of a resilient material and the slots are overlapping such that in combination they define a pivoting lever arm mechanism that is integrally connected with opposite spring arms. When a central section of the side wall section between the grooves is pushed inwardly in the direction toward the groove between the body side walls, the opposite, free end of the lever arm moves outwardly, away from the handle. A locking pin is carried on the lever arm and extends inwardly in the handle toward engagement with the blade. Since the side wall is resilient, the locking pin is normally biased toward the blade. When the blade is in the closed position the locking pin projects through a hole in the tang of the blade and thus engages the blade, locking it in the closed position. The blade is unlocked and moved into the open position by actuating the lever arm by pushing one end inwardly, toward the blade. This pivots or rocks the free end of the lever arm and thus moves the locking pin out of engagement with the tang. The engagement between the locking pin and the blade tang is thus released, allowing the blade to be pivoted about the shaft that connects the blade to the handle. The blade may be rotated to the open position. When in the fully open position the locking pin is biased into a cooperatively formed notch in the peripheral edge of the tang. The blade is locked in this open position until the lever arm is again actuated to release the locking pin from engagement with the notch. A standard blade stop pin is preferably used to stop rotational travel of the blade as it rotates from the closed to the open position.
The lever arm locking mechanism may be formed in a variety of different configurations, and the mechanism may optionally be used in combination with a fulcrum positioned between the body half that carries the lever arm and the blade.